Food crops damaged by pollution crossing continents

(PhysOrg.com) -- Man-made air pollution from North America causes Europe to lose 1.2 million tonnes of wheat a year, a new study has found.

The research, led by the University of Leeds and co-authored by the University of York, shows for the first time the extent of the Northern Hemisphere's intercontinental crop losses caused by ozone - a chemical partly produced by fossil fuels.

The study also suggests that increasing levels of air pollution from one continent may partly offset efforts to cut carbon emissions in another.

The findings have important implications for international strategies to tackle global food shortages, as well as global climate and human health strategies.

In a paper published in Biogeosciences, researchers show how ozone pollution generated in each of the Northern Hemisphere's major industrialised regions (Europe, North America and South East Asia) damages six important agricultural crops (wheat, maize, soybean, cotton, potato and rice) not only locally, but also by travelling many thousands of kilometres downwind.

Of the yield losses to Europe caused by ozone, pollution originating from North America is responsible for a 1.2 million ton annual loss of wheat. This is the biggest intercontinental ozone-related impact on any food crop. The scale of the impact of North American pollution on European wheat has previously been unknown.

Dr Steve Arnold, a senior lecturer in atmospheric composition at the University of Leeds's School of Earth and Environment, who led the study, said: "Our findings demonstrate that air pollution plays a significant role in reducing global crop productivity, and show that the negative impacts of air pollution on crops may have to be addressed at an international level rather than through local air quality policies alone."

Researchers calculated projected levels of surface ozone concentration, a powerful air pollutant that is not only harmful to human health (particularly to the respiratory system) but also damages vegetation by damaging plant cells and inhibiting plant growth .

Enhanced surface ozone concentrations are produced through a chemical combination of hydrocarbon compounds and nitrogen oxides (nitrogen oxides are emitted into the atmosphere during high temperature combustion, for example by combustion of fossil fuels by motor vehicles and in coal fired power plants).

Michael Hollaway, a PhD student at the University of Leeds, used a computer model to predict reductions in global surface ozone if man-made emissions of nitrogen oxide from the three continents were shut off. Using crop location and yield calculations, he and the research team were able to predict impacts on staple food crops, each with their own unique sensitivity to ozone pollution.

Dr Lisa Emberson a senior lecturer from the University of York's Stockholm Environment Institute and Environment Department, said: "This study highlights the need for air pollution impacts on crops to be taken more seriously as a threat to food security; currently air quality is often overlooked as a determinant of future crop supply Given the sizeable yield losses of staple crops caused by surface ozone, coupled with the challenges facing our ability to be food secure in the coming decades further coordinated international efforts should be targeted at reducing emissions of ozone forming gases across the globe."

Other findings are:

-- In terms of global crop losses, Asian pollution dominates worldwide losses of wheat (50-60%) and rice (more than 90%).
-- North American pollution contributes the most to worldwide losses of maize (60-70%) and soybean (75-85%).
-- The impact of Europe's pollution on other continents is minor due to fewer low pressure systems and weather fronts, which are responsible for transporting pollution across continents.

Dr Arnold added: "With future emissions of ozone-forming chemicals from Europe and North America expected to reduce, and emissions from Asia to increase, the findings suggest that increasing pollution from Asia may partly offset crop production benefits gained in Europe and North America through local emission reduction strategies."

More information:
The paper Intercontinental trans-boundary contributions to ozone-induced crop yield losses in the Northern Hemisphere by Michael Hollaway, Dr Steve Arnold, Prof Andy Challinor and Dr Lisa Emberson was published on 16 January 2012 and is available at: doi:10.5194/bg-9-271-2012

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part may be reproduced without the written permission. The content is provided for information purposes only.

User comments

After US completely ignoring any efforts to worldwide participation in reducing environment-unfriendly emissions (Kyoto protocol), this and the article: http://www.physor...cks.html might be a good hint that green is the way to go: messing up the place just costs money.

We can't expect such from developing countries, but areas like Japan, EU and US have the technology, wealth and knowledge to set an example on how we keep this blue&green ball blue and green.

Michael Hollaway, a PhD student at the University of Leeds, used a computer model to predict reductions in global surface ozone if man-made emissions of nitrogen oxide from the three continents were shut off. Using crop location and yield calculations, he and the research team were able to predict impacts on staple food crops, each with their own unique sensitivity to ozone pollution.

Why would you do a computer simulation if you already know the result? That's redundant. The point of a computer simulation is to make predictions. That's exactly what this article is about.If the article was about a magnetohydrodynamic simulation the response would certainly be less hostile.

Because that's the second step. They're just done doing the simulation and now they will certainly go on and look at the historical data (e.g. by comparing fod production during recession years and years with high pollution output)

You really have to come off this 'bias' trip. Scientists get paid no matter what the results of their research. They have no incentive to bias anything (actually they have a large incentive NOT to bias their data - because all those who did get found out eventually and their careers come to a crashing halt)

@dogbertSo basically what you are saying is that simulations are fine except when YOU think whatever algorithms they use are garbage. I guess we should stop making predictions about better car or airplane designs or just about every aspect of our existence all together right? Because there is no way that a simulation that predicts something can be right!

So I guess I should just not continue in my current field because I need to use computer models that are not 100% correct to predict interactions of various proteins. Thanks a lot!

So basically what you are saying is that simulations are fine except when YOU think whatever algorithms they use are garbage.

No, didn't say any such thing. There are many very good simulations. They have been tested with real data and have shown agreement with reality.

The simulation used in this article has not been validated and is unlikely to be validated since it was fed made up data. If it were the best simulation in the world, it would fail from receiving invalid input.

Try reading the article. They calculated projected levels of surface ozone. That means they made up the values used in the simulation.

Then they created a computer program which predicted the damage to crops based on nothing but the made up input and the unvalidated processes in the program.

The simulation was only used to lend credence to an incredible assertion.

So you chose a satiric comic strip character as your identity here and believe you are infallible on the subject of what data was used in this study.

That right there would tell me how much of a troll you are. Calculations aren't pulled from thin air with no regard to any promising or factual data. Data isn't just magically created and made up by the scientists on the spot.

You've never been paid to do a study. That much is obvious and a given by your bias here.

Where in your fallaciously filled argument am I suppose to be convinced that you know anything about scientific studies? Let alone anything about developing a hypothesis, theory, or law.

Like Jaeherys has implied, you really are completely clueless about high level science.

@dogbertOk, I understand better what you are saying. But projected levels implies that they have to have data to project from. That data came from sensors described in table 3 of the paper, so do you think that those values are wrong?

Finally, in the paper they calculated the contributions of NO_x levels from different regions around the planet. There have been other papers written that describe global NO_x levels (current and future) as well as the affect of NO_x levels on plant growth (by 2030 estimated to be 12-35 billion dollars).

Using this data they were able to determine the amount of loss each region has on the chosen plants, current and future. Subsequently the economic impact each region has.

So Dogbert, what you're saying is that there is absolutely no idea, no data, no measurement, on how much ozone there is at the surface level in these continents? Really?

Can't read the article can you? I said that the article notes that they 'calculated projected' levels of surface ozone concentration. I did not say that measurements have not ever been made. I pointed out that the authors of this study did not use measurement, they -- by their own words -- calculated and projected values to use in their computer simulation.

The study covered three areas that are sources of pollution (Europe, North America and South East Asia) and six crops (wheat, maize, soybean, cotton, potato and rice).

The focus of the article is on the effect of one source of pollution on one crop. However, the devil is in the details:

"-- In terms of global crop losses, Asian pollution dominates worldwide losses of wheat (50-60%) and rice (more than 90%). -- North American pollution contributes the most to worldwide losses of maize (60-70%) and soybean (75-85%). -- The impact of Europe's pollution on other continents is minor due to fewer low pressure systems and weather fronts, which are responsible for transporting pollution across continents."

The figures suggest that local pollution affects local crops most strongly.

Note that Asian pollution is responsible for at least half of all global wheat losses, not the USA.

The author cherry-picked the data to create a politically inflammatory leading sentence for this article.

He's not cherry picking data, the figures say what they say and he's not making any political statement with doing so. Besides that it's already well known the USA is a major contributor to environmental pollution.

I regard the US as a well developed 1st world country that unlike many Asian countries does not need to put the development of welfare (developing welfare requires pollution, already having it enables different sollutions) for each citizen before environmentally important issues (a reason Bush chose to ignore the Kyoto protocol).

Also if you look at emissions per capita (remember Asia makes up half the world's population and US has only around 300 million people)the figures aren't particularly in favour of debunking a politically inflammatory statement about the USA.

Can't read the article can you? I said that the article notes that they 'calculated projected' levels of surface ozone concentration.

I read the article, but unlike you I don't trust journalists to report with absolute accuracy the contents of the paper, word-by-word. Of course it has to be dumbed down and something is lost in the translation. Accusing someone of "not reading the article" in a news site is meaningless, you need to go to the source.

Open up the original paper and look at Table 3, that's where they got their data from. Is that "making up numbers out of thin air"?

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